I made a Chef repository with a great setup to roll your own Rails server and even a multi-server and multi-app infrastructure. We use this at Firmhouse to deploy our apps.
It uses nginx as the webserver and unicorn as the Rails app server. You can deploy your apps using Capistrano. It allows rolling restarts and you can add multiple Rails apps to a single server.
It also includes a preset Vagrant sample so you can test with Vagrant and VirtualBox.
Let me know if this works out for you.